Hi, I bought this unit on EBAY ,new supposedly, and im not sure how it operates, I have the manual but it is not clear what the buttons are for. I dont know what BPS stands for and if the buttons are to be in or out for tuning or calibrating. If anyone could shed some light on this it would be greatly appreciated. Thank you Lou
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MFJ-945E HF Antenna Tuner Operating Questions
- Thread starter Big Dog
- Start date
I have a similar small tuner that I use sometimes when camping, portable, etc.
First, what type of antenna are you going to use this on initially? I'm assuming you're using coax for the feedline? First switch the tuner so that it's is NOT being bypassed with that BPS switch. Set your transmitter for a low amount of power and set the tuner power switch to match the power level. Set the Transmitter and Antenna knobs so that the dash is pointing up toward 5 on each one. Now we start the tuning process.
Start by adjusting the Inductance knob. As the letter designators go higher, the inductance actually decreases and you want to use the least amount of inductance as possible. Don't transmit while moving the inductance knob, only transmit after you've changed the setting. What I do is first adjust the Inductance knob until the noise level comes up on the receiver. Then I key the transmitter and adjust the inductance and observe the results on the SWR meter. When I see the SWR start to go down, then I adjust the transmitter and antenna knobs back and forth to observe the effect on the SWR. If I don't see a SWR reduction, then adjust the inductance again. You have to move the transmitter and antenna knobs slowly because the capacitors on these little tuners are so small. When you're done, you should be able to the swr very close to 1:1. On a cross-needle meter, the Forward watts needle should be high and Reflected needle will be low or flat.
Hope that helps.
First, what type of antenna are you going to use this on initially? I'm assuming you're using coax for the feedline? First switch the tuner so that it's is NOT being bypassed with that BPS switch. Set your transmitter for a low amount of power and set the tuner power switch to match the power level. Set the Transmitter and Antenna knobs so that the dash is pointing up toward 5 on each one. Now we start the tuning process.
Start by adjusting the Inductance knob. As the letter designators go higher, the inductance actually decreases and you want to use the least amount of inductance as possible. Don't transmit while moving the inductance knob, only transmit after you've changed the setting. What I do is first adjust the Inductance knob until the noise level comes up on the receiver. Then I key the transmitter and adjust the inductance and observe the results on the SWR meter. When I see the SWR start to go down, then I adjust the transmitter and antenna knobs back and forth to observe the effect on the SWR. If I don't see a SWR reduction, then adjust the inductance again. You have to move the transmitter and antenna knobs slowly because the capacitors on these little tuners are so small. When you're done, you should be able to the swr very close to 1:1. On a cross-needle meter, the Forward watts needle should be high and Reflected needle will be low or flat.
Hope that helps.